7.3.2 Special requirements for camper trailers and boatsOn pop-up type recreational vehicles and boats, ventilation shall be effective whether the top is up or down. For camper-trailers and boats of the fully collapsible type, ventilation need only be effective when the structure is erected.7.3.3 Special requirements for RVs (motorized caravans)In motorized caravans, regardless of the location of the vehicle exhaust, vents shall not be installed in the rear wall.7.4 Position of openings — Caravans only7.4.1 Cross ventilationThe ventilation shall be provided by at least two openings fitted at opposite ends or sides of the compartment in accordance with Clauses 7.4.2 and 7.4.3.7.4.2 Distance from ceilingPermanently open ventilation equal to a minimum of 50 % of the required ventilation area shall be provided not lower than 150 mm from the highest point of the ceiling. An externally vented stove rangehood/extractor lower than 150 mm from the highest point of the ceiling shall not be used for high level ventilation.7.4.3 Distance from floorVentilation equal to a minimum of 50 % of the required ventilation area shall be provided as low as possible but not more than 150 mm from the compartment floor.NOTE Ventilation through the floor of a caravan may contravene road traffic authority requirements.7.5 Position of openings — Boats onlyEffective, unrestricted, permanent ventilation shall be provided, comprising at least two (2) openings fitted at opposite ends or sides of the cabin, or preferably, at the deck head to the underside of the deck.Where a boat otherwise meets the requirements of this Clause but it is impractical to use the boatwithout covering the permanent ventilation, a carbon monoxide detector in conformance with EN 50291-1 or UL 2034, capable of detecting low concentrations of CO and having an audible alarm shall be installed.7.6 Gas detection system required — Boats onlyWhere an appliance with a continuously burning flame is to be installed below the upper deck of a boatand there is no low level ventilation in the area where the appliance is to be installed, a combustible gasdetection system conforming to Appendix D shall be installed.NOTE If 50 % of the total ventilation required by Clause 7.3 is supplied at low level the requirement of this Clause will be satisfied.7.7 Vent warning label for caravans and boatsA permanent legible warning label with a minimum character height of 4 mm shall be affixed or adjacent to the upper and lower vents (see Clauses 7.4.2 and 7.4.3) and shall state —WARNING — THIS VENT MUST REMAIN PERMANENTLY OPEN, CLEAN AND UNRESTRICTED TO PROVIDE VENTILATION WHEN GAS APPLIANCES ARE IN USE.